Its been raining a lot here so lots of our lichens are brightly coloured and cheery.
Beautiful! Thanks for sharing!
When I saw it, I thought "this looks like it must be fluorescent under UV!". So, I looked it up, and found out that it probably isn't fluorescent (but if you have a UV flashlight to test, I am quite curious to know).
From what I can find, the yellowish green color comes from the molecule vulpinic acid. Especially interesting is that this molecule is prone to breaking down in the presence of light (terrible quality for a pigment), but a recent paper suggests that inside of the lichen the molecule sticks to polysaccharide chains in a way that dampens the molecule's photogradation pathway. The pigment can still absorb UV light but rather than dissipating the energy in a destructive process the polysaccharide holds the molecule in place and dampens the molecule's response by quickly dissipate the energy. Here is the open-access paper, and diagram below.
I also found that the name Vulpicida, Letharia vulpina, and Vulpinic acid come from folk tales about these lichens being used to poison foxes (vulpes = fox) and wolves. Not sure if it is true...
Apologize for the information dump, but I saw the bright colors and just had to look into its photophysics ๐
Thanks for the read, I appreciate it. I did pass my UV light over it and no fluorescence. I thought the lower cortex may have been lighting up but probably just looked brighter than the rest of the thallus due to the lighter colour. I always carry a uv light with me but I'm terrible for leaving it in my pocket haha
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